docs: def ssh_keyscan(cls, vm_id):
          """Wipe this old key and learn the new one from a freshly
          created vm. This is a security risk for this VM, however
          we dont have another way to learn the key yet, so do this
          for the user."""
          cls.echo('Wiping old key and learning the new one')
          _version, ip_addr = cls.vm_ip(vm_id)
          cls.execute('ssh-keygen -R "%s"' % ip_addr)
  
          for _ in range(5):
              output = cls.exec_output('ssh-keyscan "%s"' % ip_addr)
              if output:
                  with open(os.path.expanduser('~/.ssh/known_hosts'), 'a') as f:
                      f.write(output)
                  return True
              time.sleep(.5)